/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_offset_q15.c
*
* Description:	Q15 vector offset.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated.
*
* Version 0.0.7  2010/06/10
*    Misra-C changes done
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup offset
 * @{
 */

/**
 * @brief  Adds a constant offset to a Q15 vector.
 * @param[in]  *pSrc points to the input vector
 * @param[in]  offset is the offset to be added
 * @param[out]  *pDst points to the output vector
 * @param[in]  blockSize number of samples in the vector
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function uses saturating arithmetic.
 * Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.
 */

void arm_offset_q15(
    q15_t* pSrc,
    q15_t offset,
    q15_t* pDst,
    uint32_t blockSize)
{
	uint32_t blkCnt;                               /* loop counter */

#ifndef ARM_MATH_CM0

	/* Run the below code for Cortex-M4 and Cortex-M3 */
	q31_t offset_packed;                           /* Offset packed to 32 bit */


	/*loop Unrolling */
	blkCnt = blockSize >> 2u;

	/* Offset is packed to 32 bit in order to use SIMD32 for addition */
	offset_packed = __PKHBT(offset, offset, 16);

	/* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
	 ** a second loop below computes the remaining 1 to 3 samples. */
	while(blkCnt > 0u) {
		/* C = A + offset */
		/* Add offset and then store the results in the destination buffer, 2 samples at a time. */
		*__SIMD32(pDst)++ = __QADD16(*__SIMD32(pSrc)++, offset_packed);
		*__SIMD32(pDst)++ = __QADD16(*__SIMD32(pSrc)++, offset_packed);

		/* Decrement the loop counter */
		blkCnt--;
	}

	/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
	 ** No loop unrolling is used. */
	blkCnt = blockSize % 0x4u;

	while(blkCnt > 0u) {
		/* C = A + offset */
		/* Add offset and then store the results in the destination buffer. */
		*pDst++ = (q15_t) __QADD16(*pSrc++, offset);

		/* Decrement the loop counter */
		blkCnt--;
	}

#else

	/* Run the below code for Cortex-M0 */

	/* Initialize blkCnt with number of samples */
	blkCnt = blockSize;

	while(blkCnt > 0u) {
		/* C = A + offset */
		/* Add offset and then store the results in the destination buffer. */
		*pDst++ = (q15_t) __SSAT(((q31_t) * pSrc++ + offset), 16);

		/* Decrement the loop counter */
		blkCnt--;
	}

#endif /* #ifndef ARM_MATH_CM0 */

}

/**
 * @} end of offset group
 */
